Dentists always try to match the shade of a restoration to an existing tooth in the patient's mouth. Historically, this takes place by bringing the patient to a nearby window using daylight as the light source. Literature suggests that the color temperature of 5500 degrees Kelvin be used as a standard light spectrum that represents light on a cloudy bright day at 12 o'clock noon.
Some current devices use florescent lamps or LED's to produce a standard light spectrum of 5500 Kelvin. However, when tooth shades are matched with the 5500 Kelvin light spectra there still remains a significant chance the restoration shade will not match the existing tooth shade under different lighting conditions. There are very expensive spectrophotometers that aid in tooth shade selection. These devices typically sell for more than ten times the cost of our invention. However, they only measure the tooth shade at one wavelength spectra.
For example, the dentist matches the shade at 5500 degrees Kelvin and it looks good in the dental office.
The patient goes home and looks at their restoration in their bathroom light which happens to be an incandescent lamp. They then call the doctor to say the shade “changed”. This happens because what the doctor thought was a perfect match was only a good match but not perfect. In physics there is a principal called metamerism. Metamerism says that if a shade matches absolutely perfectly it should match in all color spectra, i.e., with all different light sources.